7.62x39mm
The 7.62x39mm rifle cartridge was designed during World War II and first used in the SKS carbine by the Soviet Union. Use of the cartridge is widespread by (Top). 7.62x39mm (Bottom).]]both militaries and civilians. This is due primarily to the proliferation of the SKS and AK-47 pattern rifles during the 20th century. The cartridge was likely influenced by a variety of foreign developments, especially the pre-war German GeCo, 7.75x39mm experimental round, and possibly by the late-war German 7.92x33mm Kurz ("Kurz" meaning "short" in German). Shortly after the war, the world's most recognized military pattern rifle was designed for this cartridge: the AK-47. The cartridge remained the Soviet standard until the 1970s, and is still one of the most common intermediate rifle cartridges used around the world. It was superseded by the 5.45x39mm cartridge which is used by the current issue AK-74. History The original Soviet M43 bullets are boat-tail bullets with a copper-plated steel jacket, a large steel core, and some lead between the core and the jacket. The cartridge itself consists of a berdan-primed, highly tapered (usually steel) case which seats the bullet and contains the powder charge. The taper makes it very easy to feed and extract the round, since there is little contact with the chamber walls until the round is fully seated. This taper is what causes the AK-47 to have distinctively curved magazines. While the bullet design has gone through a few redesigns, the cartridge itself remains largely unchanged. M43 Although the new cartridge represented a great leap forward from previous designs, the initial bullet design was flawed. The complete solidity of the M43 projectile causes its only drawback—it is very stable, even while traversing tissue. It begins to yaw only after traversing nearly 30 cm (one foot) of tissue. This greatly reduces the wounding effectiveness of the projectile against humans. Dr. Martin Fackler noted that the wounds from the M43 round were comparable to that of a small handgun round using non-expanding bullets. Unless the round struck something vital, the wound was usually non-fatal, small and quick to heal. M67 In the 1960s the Yugoslavians experimented with new bullet designs to produce a round with a superior wounding profile, speed, and accuracy to the M43. Dr. Fackler also evaluated the M67 in the same manner that he evaluated the M43. The M67 projectile is shorter and flatter-based than the M43. This is mainly due to the deletion of the mild steel insert. This has the side effect of shifting the center of gravity rearward in comparison to the M43. This allows the projectile to destabilize nearly 17 cm earlier in tissue. This causes a pair of large stretch cavities at a depth likely to cause effective wound trauma. When the temporary stretch cavity intersects with the skin at the exit area, a larger exit wound will result, which takes longer to heal. Additionally, when the stretch cavity intersects a stiff organ like the liver, it will cause damage to that organ. However, without fragmentation, the wounding potential of M67 is mostly limited to the small permanent wound channel the bullet itself makes. While a fragmenting round (like the 5.56x45mm NATO) might cause massive tissue trauma and blood loss (and thus rapid incapacitation) on a lung or abdominal hit, the M67 has a greater chance of merely wounding the target. However, the 5.56x45 will only reliably fragment in close ranges below 125 meters. Many contemporary Russian-made 7.62x39 cartridges, such as those sold under the brand names Wolf and Golden Tiger feature a modified M67 bullet with an airspace cast into the nose or similar ballistic-enhancing tip design (e.g. 8m3) which improve fragmentation and/or tumbling tendencies. Chinese steel core Chinese military-issue ammunition in this caliber is M43 style with a mild steel core and a thin jacket of copper or brass. Contrary to common belief, the use of steel was a cost saving measure rather than one to increase penetration. Additionally, mild steel is not sufficiently hard to grant unusual armor penetrating capability. Despite this, Chinese ammunition (as well as all other M43 ammunition) is currently banned from importation in the US. This is because 7.62x39mm caliber handguns exist, and U.S. federal law classifies the round as an armor-piercing handgun round. This classification is based on materials and bullet design rather than on empirical ability to penetrate armor. Ballistics The standard AK-47 or AKM fires a 7.62x39mm round with a muzzle velocity of 710 metres per second (2,329 ft/s). Muzzle energy is 2,010 joules (1,467 ft·lbf). Cartridge case length is 38.6 millimetres (1.5 in), weight is 18.21 grams (281.0 grains). Projectile weight is normally 8 grams (123 gr). The AK-47 and AKM, with the 7.62x39mm cartridge, have a maximum effective range of around 400 meters. Cartridge dimensions The 7.62x39mm has 2.31 ml (35.6 grains H2O) cartridge case capacity. 7.62x39mm maximum C.I.P. cartridge dimensions. All sizes in millimeters (mm). Americans would define the shoulder angle at alpha/2 ≈ 16.4 degrees. The common rifling twist rate for this cartridge is240 mm (1 in 9.45 in), 4 grooves, Ø lands = 7.62 millimetres (0.300 in), Ø grooves = 7.92 millimetres (0.312 in), land width = 3.81 millimetres (0.150 in) and the primer type is small rifle. According to an American source some barrels can however have a non C.I.P. conform grooves diameter of 7.82 millimetres (0.308 in). According to the official C.I.P. (Commission Internationale Permanente Pour L'Epreuve Des Armes A Feu Portative) guidelines the 7.62x39mm case can handle up to 355 MPa (51,488 psi) piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers. Other names for 7.62x39mm On some occasions, this ammunition is referred to as 7.62 mm Soviet, 7.62 mm Warsaw Pact, or 7.62 mm ComBloc. It was also known in the United States as .30 Short Russian/ComBloc; the "Short" was to distinguish it from the older .30 Russian, which was the 7.62x54mmR. Hunting and sport use Since approximately 1990, the 7.62x39mm cartridge has seen some use in hunting arms in the US for hunting game up to the size of whitetail deer, as it is approximately as powerful as the .30-30 Winchester round, and has a similar ballistic profile. Large numbers of inexpensive imported semiautomatic rifles, like the SKS and AK-47 clones and variants, are available in this caliber. In addition, Ruger produces the Mini-30 as a 7.62x39mm version of their popular Mini-14 rifle. The low cost and high availability of military surplus ammunition makes this cartridge attractive for many civilian shooters. Category:Ammunition